This invention relates to a floating seal system for rotary devices to reduce gas leakage around the rotary device in a duct and across the face of the device to an adjacent duct. Principal uses of such rotary devices including regenerative exchangers for vapor or chemical removal or heat exchange. Typically, the rotary regenerative exchangers embody the use of exchange material wheels mounted for rotation on an axle or by peripheral gears. Supported between the center hub and outer rim is the exchange material having gas passage essentially parallel to central axis. The rotary regenerative exchangers usually pass through adjacent ducted treatment and regenerative gas streams.
Early use of the rotary regenerative exchangers required precise fabrication of both housing and exchanger wheel assembly due to poor sealing mechanisms. Short circuiting of gas across the face or around the perimeter of the exchanger wheel results in a significant decrease in exchanger efficiency. The precise fabrication required to maintain an acceptable efficiency in the absence of adequate seal systems imposes severe limitations on the use of such rotary regenerative exchangers. Less precise fabrication methods not only require better seal systems to prevent short circuiting, but require the seal system compensate for axial misalignment and uneveness of the regenerator wheel contact surfaces.
U.S. Pat. No. 3,931,852 teaches a seal system for rotary regenerator exchangers with a circular cermic regenerator core. The seal system comprises a plurality of monolithic ceramic seal elements assembled in generally end to end relationship to form peripheral and radial seals. Monolithic seal elements are located within cavities with heat resistant resilient material beneath the seals being cooled by air flow. Likewise, U.S. Pat. No. 4,024,905 teaches a seal system for rotary ceramic heat exchangers fitted to gas turbines wherein U-shaped sealing shoes are held against the rotating ceramic heat exchanger surface by a plurality of springs. The plurality of seal springs compensate for the non-planar condition of the heat exchanger wheel. The two aforementioned seal systems directly contact the surface of the porous ceramic heat exchange wheel used in gas turbines. This type of direct contacting seal is not acceptable for rotary exchangers having soft, easily scored surfaces, such as moisture exchanger wheels for adsorption air conditioning equipment. The present invention differs from the direct contacting seal in that it is suitable for soft surface paper or asbestos moisture exchanger wheels since the seal assembly does not come into direct contact with exchange wheel material.
U.S. Pat. No. 4,024,906 teaches a seal system for maintaining separation of fluids in a gas turbine comprising an arcuate portion co-axial with the matrix and a transverse portion extending diametrically, each seal secured to a pressure plate engaging the end face of the matrix. As with the aforementioned seal systems, the seal system of U.S. Pat. No. 4,024,906 relies on direct contact between seal and exchange material and, therefore, cannot be used with relatively delicate absorbent or adsorbent exchanger materials.
The floating seal system taught by U.S. Pat. No. 3,907,310 overcomes many of the disadvantages referred to above. However, the seal system taught by the U.S. Pat. No. 3,907,310 does not provide desired extent of prevention of gas leakage due primarily to stiffness of the components resulting from their structural design and due to excessive leakage at the juncture of the radial and peripheral seals.